In a world of increasing trauma exposure, post-traumatic stress disorder (PTSD) is a major public health concern. With estimates ranging between 37%-92% of individuals exposed to severe trauma during their lifetime, both civilian and combat PTSD are common and debilitating. Despite this prevalence and despite our advancing knowledge of the neurobiology of fear, there are no currently accepted interventions for the early intervention and prevention of PTSD in the immediate aftermath of trauma. The initial symptoms of PTSD can be considered part of the normal reaction to trauma, but, those who suffer from chronic PTSD do not recover in the weeks and months following a trauma the way others do. Those with PTSD may not worsen, but they don't extinguish their original fear reactions. Therefore, PTSD can be viewed as a failure of recovery caused in part by a failure of fear extinction following trauma. We propose a pilot study, based on translational models of the consolidation of fear memories, to begin to examine the effects of early interventional extinction training in an ultimate effort to know when it is best to intervene with humans following exposure to trauma. The existing evidence suggests that 1) the debriefing literature is equivocal at best with some studies indicating it can cause harm, 2) there are no good candidates for immediate intervention;3) the animal evidence suggests that some immediate extinction training can result in decreases in spontaneous recovery and renewal and reinstatement;4) the animal evidence suggests that incomplete extinction training may cause sensitization, and finally;5) the timing of extinction training after exposure/conditioning is crucial. Therefore, we propose to test very early interventions following exposure to trauma in humans in the emergency department (ED). For this pilot study, we will randomly assign rape survivors presenting at the ED to one of the following 2 conditions: 1) `Immediate Treatment'Group: which includes immediate prolonged exposure therapy (PE) in ED plus delayed PE (3 sessions total);2) or `Assessment only'group. Additionally for a secondary predictive outcome analysis, in all subjects we will examine predictors for response including biomarkers - biological and genetic measures, sociological predictors, and psychological predictors in the ED, and at 4 and 12 week follow-up sessions. The overall aim of this project is to gather pilot data to begin to determine if exposure therapy in the immediate aftermath of trauma can prevent the development of PTSD. The long term goals are to establish pharmacological and psychotherapeutic interventions in the immediate aftermath of trauma to reduce the likelihood of developing a durable fear response such as PTSD.